LC Enantioseparation of b-Lactam Stereoisomers through the Use of b-Cyclodextrin-Based Chiral Stationary Phases Ga ´bor Fodor 1 , Istva ´n Ilisz 1,& , Julianna Szema ´n 2 , Ro ´bert Iva ´nyi 2 , Lajos Szente 2 , Ga ´bor Varga 3 , Enik} o Forro ´ 4 , Ferenc Fu ¨lo ¨p 4 , Antal Pe ´ter 1 1 Department of Inorganic and Analytical Chemistry, University of Szeged, 6720 Szeged Do ´m te ´r 7, Hungary; E-Mail: ilisz@chem.u-szeged.hu 2 CycloLab R&D Ltd, Budapest, 1097 Illatos u ´t 7, Hungary 3 ChiroQuest Chiral Technologies Development Ltd, Budapest, 1075 Rumbach, Hungary 4 Institute of Pharmaceutical Chemistry, University of Szeged, Szeged, Hungary Received: 11 November 2009 / Revised: 19 January 2010 / Accepted: 21 January 2010 Online publication: 2 April 2010 Abstract Direct liquid chromatographic methods were developed to investigate the enantioseparation of 19 b-lactams on three cyclodextrin-bonded chiral stationary phases: permethyl-b-cyclo- dextrin, b-cyclodextrin and R,S-hydroxypropyl-b-cyclodextrin, prepared by a novel synthetic route. 17 of the 19 b-lactam stereoisomers were partially or baseline-separated on at least one of the tested chiral stationary phases. The influence of the structures of the b-lactams (the positions and types of the substituents, the size of the attached rings) on the enantiomer separation is discussed. The permethylated b-cyclodextrin selector proved to be the most effective one for the tested analytes. Keywords Column liquid chromatography Chiral separations Cyclodextrin-based chiral stationary phase b-Lactams Introduction b-Lactams have become a topic of interest in chemistry in the past few years, because they are the most widely used types of antibiotics. Their antibac- terial functions result in the four-mem- bered b-lactam ring inhibiting formation of the bacterial cell wall [1–4]. b-Lactams are also used as intermediates in the synthesis of b-amino acids [5], short peptide segments [6] and alkaloids [7]. Consequently, a number of direct and indirect enzymatic [8, 9] and enantiose- lective synthesis [10] of b-lactams have recently been reported. Since the biological activities of b-lactams depend on their stereochem- istry, there is a great need for the avail- ability of pure enantiomers. Liquid chromatography (LC) with chiral sta- tionary phases (CSPs) have been widely used for enantioseparations [11–21]. The separation of lactam enantiomers through the use of different LC CSPs has been reported [16–21]. Most of the b-lactam stereoisomers presented in this paper were separated by Pe´ter et al. by means of an LC method [16] on macro- cyclic glycopeptide CSPs. Although the separation of lactams (1-12, see Table 1) has previously been studied on cyclo- dextrin bonded CSPs [21], our present aim was to evaluate LC methods for the enantioseparation of 19 b-lactams on three cyclodextrin-bonded CSPs Presented at: 8th Balaton Symposium on High-Performance Separation Methods, Siofok, Hungary, September 2–4, 2009. 2010, 71, S29–S34 DOI: 10.1365/s10337-010-1514-0 Ó 2010 Vieweg+Teubner | GWV Fachverlage GmbH Original Chromatographia Supplement Vol. 71, 2010 S29